This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bronchiolitis is the number one reason children younger than 1 year are hospitalized. This common disease is caused by an infection, usually a virus. Despite how common this disease is, little research has studied which children with bronchiolitis are at risk for severe problems, and no research has studied when it is safe for infants to be discharged home from the hospital. The purpose of this study is: (1) To elucidate the role of multiple pathogen infections and to determine the utility of PCR-testing for an infectious etiology;(2) To create high-risk and low-risk clinical rules to predict reliably those children with bronchiolitis who would require continuous positive airway pressure or intubation and those who would not require intensive care;and (3) To develop hospital discharge guidelines that encourage earlier but safe discharges and foster family-centered care.